Medical device lock mechanism

ABSTRACT

A medical device ( 10 ) includes an implant body ( 20 ) with a number of segments ( 30 ) hingedly interconnected so as to assume a straightened state for delivery and a flexed or roughly curved deployed state. Implant body may have engagement elements on at least two different segments, for example on a majority of segments. An elongated locking element anchored at the distal segment of the implant body may have projections for at least each engagement element. Tension applied to the locking element biases the implant body from the straightened state to the flexed deployed state. When the locking element is deflected to reach the curved deployed state, flexing segments of the implant body lock by matching engagement elements of the implant body with projections of the locking element. A very secure lock may be formed to prevent opening after deployment.

The present invention claims priority to U.S. provisional patentapplication No. 61/304,857 filed 16 Feb. 2010 by Applicant Siegal.

FIELD AND BACKGROUND OF THE INVENTION

The present invention relates to implant bodies, such as for spinalsurgery and, in particular, it concerns an implant device having a verystable locking arrangement to prevent the implant body from opening uponce implanted into the body.

Various devices have been proposed for implants and their deploymentinside the spine or other parts of the body. An important feature of animplant is that it not only be delivered effectively but that it remainin position after deployment and not open in the body. Stability and asecure and reliable placement of the implant are critical. If theimplant were to open after deployment, it could damage surroundingtissue and undo the effects of the spinal surgery.

PCT patent application publication no. WO 2009/019669 of Applicantpublished 12 Feb. 2009 teaches an implant including an implant body andan elongated tightening element that is introduced into a body in astraightened configuration and then assumes a roughly curvedconfiguration within the body. The aforementioned publication is herebyincorporated by reference herein in its entirety.

It would therefore be highly advantageous to provide an implant (andassociated method) that will not open in the body after deployment, forexample for spinal surgery.

SUMMARY OF THE INVENTION

In accordance with one aspect of the present invention, there isprovided a medical device comprising (a) an implant body including aplurality of segments interconnected so as to assume a straightenedstate and a flexed deployed state, the implant body formed with at leasttwo engagement elements, each of at least two different segments havingan engagement element; and (b) an elongated locking element anchored atone segment of said implant body, the locking element having at leasttwo projections corresponding to the at least two engagement elements,wherein said implant body and said locking element are configured tolock, such that when said locking element is deflected to reach saidflexed deployed state, the at least two projections of the lockingelement engage and lock with the at least two engagement elements of theimplant body, each locking segment remaining locked after successivesegments flex and lock, said locking arrangement being effective to locksaid locking element relative to said implant body, thereby retainingsaid implant in said flexed deployed state.

A further aspect of the present invention is a medical device,comprising

(a) an implant body including a plurality of segments interconnected soas to assume a straightened state and a flexed deployed state, theimplant body having at least two sockets, each of at least two differentsegments having a socket; and

(b) an elongated locking element anchored at one segment of said implantbody, the locking element having at least two bulges corresponding tothe at least two sockets, wherein said implant body and said lockingelement are configured to lock such that when said locking element isdeflected to reach said flexed deployed state the et least two bulges ofthe locking element engage and lock with the at least two sockets of theimplant body, said looking arrangement being effective to lock saidlocking element relative to said implant body in a plurality ofsegments, thereby retaining said implant in said flexed deployed state.

A still further aspect of the present invention is a method fordeploying a medical device within a subject's body, comprising (a)providing an implant body including a plurality of segmentsinterconnected so as to assume a straightened state and deflectable toassume a flexed deployed state, a plurality of said segments each havingan engagement element; (b) providing a locking element anchored to oneof at least two different segments and extending along said implant bodyalong a direction of elongation of the implant body, the locking elementhaving projections corresponding to each of the engagement elements; and(c) advancing the implant body into the subject's body and applyingrearward tension on said locking element such that the implant body isdeflected to said flexed deployed state, where said projections matewith corresponding of said engagement elements so as to lockcorresponding segments in said flexed deployed state.

These and other features, aspects and advantages of the presentinvention will become better understood with reference to the followingdrawings, descriptions and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is herein described, by way of example only, withreference to the accompanying drawings, wherein:

FIG. 1 is an isometric view of an implant including an implant bodyhaving a tightening element engaged to the implant body, in accordancewith one embodiment of the present invention;

FIG. 2 is a partial view of FIG. 1 broken away to show engagement of thetightening element with projections of the implant body, in accordancewith one embodiment of the present invention;

FIG. 3 is an isometric view of the implant of FIG. 1 with all but onesegment in the flexed deployed state, in accordance with one embodimentof the present invention;

FIG. 4 is a partial side view of the flexed implant of FIG. 3 brokenaway to show engagement of the tightening element with projections ofthe implant body, in accordance with one embodiment of the presentinvention;

FIG. 5 is an enlarged view of the region of FIG. 4 denoted by the circleshowing a locking arrangement of the implant, in accordance with oneembodiment of the present invention;

FIG. 6 is an isometric view of an implant in a straightened state,including an implant body and a tightening element engaged to theimplant body, in accordance with one further embodiment of the presentinvention;

FIG. 7 is an isometric view of the implant of FIG. 6 in its flexeddeployed state, in accordance with one embodiment of the presentinvention;

FIG. 8 is a partial view of FIG. 7 broken away to show engagement of thebulges of the tightening element with sockets of the implant body, inaccordance with one embodiment of the present invention;

FIG. 9 is an isometric view of a tightening element engaged to animplant body, in accordance with one further embodiment of the presentinvention;

FIG. 10 is a side view of the tightening element of FIG. 9;

FIG. 11 is a sectional view of two segments of the locking mechanism ofthe implant of FIGS. 9-10 with the implant in a straightened state, inaccordance with embodiment of the present invention;

FIG. 12 is a sectional view of the two segments of the locking mechanismof the implant of FIGS. 9-10 with the implant in a flexed deployedstate, in accordance with one embodiment of the present invention; and

FIG. 13 is a flow chart showing a method of the present invention.

FIG. 14A is an isometric view of an implant including an implant body ina straightened state and having a locking element engaged to the implantbody, in accordance with one embodiment of the present invention;

FIG. 14B is a sectional view of FIG. 14A show engagement of the lockingelement with projections of the implant body, in accordance with oneembodiment of the present invention;

FIG. 15A is an isometric view of the implant of FIG. 14A with all butone segment in the flexed deployed state, in accordance with oneembodiment of the present invention;

FIG. 15B is a sectional view of the flexed implant of FIG. 15A showingengagement of the locking element with projections of the implant body,in accordance with one embodiment of the present invention;

FIG. 16A is an isometric view of an implant in a straightened state,including an implant body and a locking element engaged to the implantbody, in accordance with one further embodiment of the presentinvention;

FIG. 16B is an isometric view of the implant of FIG. 16A in its flexeddeployed state, in accordance with one embodiment of the presentinvention; and

FIG. 16C is a sectional view of FIG. 16B showing engagement of thebulges of the locking element with sockets of the implant body, inaccordance with one embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is an implant that may be used in the human body,lot example during spinal surgery of various types. The implant may havea stable and secure locking arrangement. The present invention alsoincludes a corresponding method for deploying the implant through adelivery conduit. The implant may include an implant body and a lockingelement. The locking arrangement may include projections on the lockingelement that may mate with engagement elements on the segments of theimplant body along the flexing portion of the implant body. Theprojections may be bulges, teeth, elastic tabs, etc. The engagementelements may be steps, sockets, rectangular openings, etc. As eachsegment flexes, the projections fall into place in the engagementdements and the implant may be unable to open inside the body in whichit has been placed.

In contrast to the prior art, in which the implant locking arrangementonly involves locking one segment of the implant body, the implant ofthe present invention may involve locking all the segments of theimplant that have flexed, or in other embodiments at least two or atleast three or at least one third or at least one-fourth or at least amajority of such segments. In further contrast to the prior art, inwhich the implant body does not have a locking arrangement that isstable, the implant of the present invention may lock in a stable andsecure enough manner that the implant body may not open while in thebody once it is locked in its flexed deployed state. In still furthercontrast to the prior art, in which the implant may lock with a singleresilient tooth, the implant body of the present invention may lock withprojections on segments of the implant body mating with complementaryrecesses on the locking element. In contrast to the prior art, thelocking arrangement may comprise the mating of a plurality of bulges onmultiple segments with a plurality of sockets or recesses on at leasttwo segments, and in some embodiments on all the segments. In furthercontrast to the prior art, the bulge to bulge length may be smaller thanthe flexion region to flexion region length from one segment to itsadjacent segment. As a result, bulges of the locking element that maynot be in sockets in the straightened state may lock into sockets oncethe segments flex into the flexed deployed state. The result is extrastability of the locking arrangement.

The principles and operation of medical device locking mechanisms andmethods according to the present invention may be better understood withreference to the drawings and the accompanying description.

Referring now to the drawings, FIGS. 1-5 show one embodiment of amedical device, the medical device 10 comprising an implant body 20including a plurality of segments 30 interconnected at flexion regions35, for example hingedly, so as to assume a straightened state and aflexed deployed state. The flexion region 35 may comprise a conventionalhinge 35, an integral hinge or another structure providing the requiredinter-segment flexibility. As part of the locking arrangement or lockingmechanism, implant body 20 may be formed with at least two engagementelements 40, each of at least two different segments, for example 30A,30B having an engagement element 40.

Preferably, at least three segments 30 have an engagement element 40 andlock with a projection 60. In other preferred embodiments, at least athird of the segments 30 have an engagement element 40 and lock with aprojection 60. In a further preferred embodiment, at least one segment30 of each consecutive four segments 30 has an engagement element 40 andlocks with a projection 60 of the elongated element 50. In otherembodiments, more than half of the segments 30 have an engagementelement. In one preferred embodiment, each of the segments 30 other thana distal segment 30 may have an engagement element 40 (which should beunderstood as not absolutely precluding the distal segment from alsohaving an engagement element).

Medical device 10, which may be an implant 10, may also have anelongated locking element 50 that may be anchored at a distal segment ofsaid implant body. In this regard “a distal segment” of the implant bodyshall be understood to refer to the most distal segment that is capableof flexing. Locking element 50 may have at least two projections 60corresponding to the at least two engagement elements 40. Preferably,locking element 50 may have at least one projection 60 corresponding toand engaging a majority of each engagement element 40 of implant body 20to implement the locking arrangement.

Implant body 20 and locking element 50 may be configured such thattension applied to tightening element 50 tends to bias implant body 20from its straightened state to its flexed deployed state. Elongatedlocking element 50 may pass along a channel extending along implant body10.

Implant body 20 and elongated locking element 50 may be configured tolock securely and with stability to prevent implant 10 from opening onceemplaced in its flexed state in the spine or other part of the body.This locking may be such that when locking element 50 is deflected toreach the flexed deployed state (as part of implant body 20), eachsuccessive segment 30 of implant body 20 may flex and the at least twoprojections 60 of elongated locking element 50 may engage and lock withthe at least two engagement elements 40 of implant body 20. Each lockingsegment 30 may remain locked after one or more successive segments flexand lock. Accordingly, the locking arrangement is effective to lock thelocking element 50 relative to implant body 20, thereby retainingimplant 10 in said flexed deployed state in the body.

By way of example, each of at least two or at least three or at leastone-third of the segments or at least one-fourth of the segments or atleast the majority of the segments or at least one out of every fourconsecutive segments, of said implant body may for example be formedwith at least one engagement element so as to lock with the lockingelement. Further, the locking element may have a projectioncorresponding to and engaging each of the engagement elements of theimplant body to provide said locking arrangement. Alternatively, lockingelement 50 may have a multiplicity of projections 60 but may have lessthan one projection for each engagement element 40 of implant body 20.In some preferred embodiments, the locking element 50 may have many moreprojections than there are engagement elements of the implant body. Forexample every fourth projection 60 may lock with an engagement element.In some cases, moreover, each segment 30 may have multiple engagementelements 40.

The projections 60 and engagement elements 40 may encompass a variety ofshapes including cross-sectional shapes. In general, engagement elements40 of implant body 20 are broadly defined to include a step, a slot orany shape that can receive and “catch” the projection 60 (i.e. a bulge,tooth or elastic tab) of locking element 50. In the embodiment of FIGS.1-5, engagement elements 40 may be described as steps 40 that may catchteeth 60 projecting from locking element 50. The structure anddimensions of projections 60 may be chosen according to the mechanicalproperties of the materials used to provide sufficient resilience andsecure locking, and in accordance with considerations ofbiocompatibility. The corresponding engagement elements may beimplemented as any suitably positioned element or recess, for example anupward projection or a recessed notch, or a combination thereof.

In FIGS. 6-8, the engagement elements may be described as sockets 40 andthe projections may be described as bulges 60. The term “bulge” is notlimited to a rounded bulge, even though in some embodiments, such asFIGS. 6-8, bulges 60 may be spherical. Similarly, the term “socket” isnot necessarily referring to a rounded socket, although in FIGS. 6-8sockets 40 are rounded. Furthermore, it is contemplated that projections60, including bulges 60, could be solid or hollow.

In the embodiment shown in FIGS. 9-12, the projections 60 may bedescribed as elastic tabs 60 and engagement elements 40 may becomplementary recesses 40. For example, each segment 30 may have atleast one complementary recess and at least one elastic tab oftightening element 60 may lock with the at least one complementaryrecess 40 of each segment 30 as each segment flexes in the flexeddeployed state.

In FIGS. 9-12, implant body 200 may have segments 220 and a zipper-likelocking element 210 that may be rigidly attached to a distal segment 220and that may be engaged in all segments of the implant 200. The proximalend of locking element 210 can be pulled in a rearward directionrelative to implant body 200. Implant body 200

may have recesses 222 or slots. Locking element 210 may be a strip andmay be implemented for example using metal (e.g., Nitinol, StainlessSteel) or plastic (e.g., PEEK, UHMWPE), and has a series of elastic tabs212 which may latch onto the corresponding engagement elements 222 ofimplant body 200.

FIGS. 11-12 show the actual locking mechanism in between two adjacentsegments 220. FIG. 11 shows two segments 220 in the straightened stateof implant body 200 whereby a notch or opening (which is V-shaped inthis embodiment) appears between each of the two consecutive segments220. Once locking element 210 is pulled in the rearward direction inaccordance with arrow R in FIG. 11) relative to segments 220, segments220 rotate due to the offset between an axis of segments 220 and achannel through which the tightening element 210 passes. As a result ofthe rotation, segments 220 now close upon each other internally as shownin FIG. 12. As also shown in FIG. 12, the elastic tabs 212 are lockedinside slots 222 and as a result segments 220 are attached with eachother and are strongly locked.

In some embodiments, a tensioning element separate from locking element50 (or 210) may be used to pull the implant body in a rearward directionand induce flexing of its segments 30. In that case the tensioningelement would be used to first cause the device 10 to flex. Then,locking element 50 may be pulled to lock the device by matingprojections 60 with engagement elements 40.

The locking mechanism of the present invention in any of the aboveembodiments may be further enhanced by using multiple locking elements(50 or 210). In this case, multiple projections of implant body (200 or20) within a segment may engage and lock with multiple engagementelements (222 or 40) on each segment (220 or 30) of implant body. In oneexample, the multiple locking elements may be side by side strips ofmaterial.

The medical device 10 of the present invention may further include aconduit sized to receive the medical device 10, for example when themedical device 10 is in its straightened shape, and to maintain theimplant body 20 in the straightened state. The conduit may be straightin shape and may be close-fitting to the external shape of implant 10.Although the conduit is not shown in FIGS. 1-3 herein, an example of aconduit that may be used for an implant 10 of the present invention isshown in FIGS. 2-3 of publication WO 2006/072941 published 13 Jul. 2006.Implant body 20 and locking element 50 may be configured to lock suchthat when said locking element is deflected to reach the flexed deployedstate each successive segment flexes and the projections of the lockingelement engage and look with the engagement elements of the implantbody. In FIG. 6, when implant body is in a straightened state,projections 60 of locking element 50, which in FIG. 6 may be bulges 60,may not necessarily be situated in or engaged to, and indeed likely arenot situated in or engaged to, engagement elements 40, which in FIG. 6may be described as sockets 40, of implant body 20. In FIG. 7, onlythose segments 30 that have already flexed (30A, 30B) may have theirengagement elements or sockets 40 occupied by bulges 60. Further, inFIG. 8, it is more easily seen that bulges 60 are in sockets 40 forflexed segments 30. A careful inspection of FIGS. 6-8 and in particularFIG. 8 reveals that in the implant 10 a length from a bulge 60A to thenearest adjacent bulge 60B may be shorter than a length from a flexionsection 35A of a segment 30A, to a flexion section 35B of an adjacentsegment 30B. It should be noted that in the embodiment of FIGS. 6-8 thelength from bulge 40 to bulge 40 (i.e. to adjacent bulge 60) may besubstantially uniform and similarly the length from socket to socket(i.e. to adjacent socket 40) may be substantially uniform. However, inan embodiment in which the medical is helical or non-planar or where anon-uniform curvature of the medical device is required, these distancesmay not be uniform, although socket to socket distance may still matchbulge to bulge distances at flexing segments.

It is noted that as successive segments 30A, 30B, 30C, 30D flex, theroughly arcuate shape of tightening element 50 may span a smaller arethan the roughly arcuate shape of the hinges 35 of implant body 20. Thisis because in a flexed deployed state, tightening element 50 of implant10 is inward of most of implant body 20, and in particular is inward ofhinges 35. In this regard, “inward” is described relative to closenessto the center of the arc/circle made by the arcuate form of implant 10(locking element 50 and implant body 20) in its flexed deployed state.Accordingly, in the straightened state at least some of the bulges ofthe locking element may be situated in portions of hinges outside thesockets and in the flexed deployed state the bulges of the lockingelement are situated in the sockets of flexed segments. Each segment 30that has flexed may have a bulge 60 that is engaged to its correspondingsocket. As seen from FIG. 8, in the flexed deployed state, every flexedsegment that has a socket also has a bulge situated therein.

Although the drawings illustrate embodiments in which the implant flexesin a two dimensional plane so that the direction of elongation ofimplant 10 may be said to be substantially co-planar with hinges andperpendicular to the hinges 35 in that plane, the present invention isequally applicable to nonplanar or helical forms of the implant 10, suchas where a direction of elongation of the implant running from a distalflexing segment to a proximal flexing segment in the flexed deployedstate is not perpendicular to the hinges of the segments that flex. Anexample of a helical configuration of implant without the lockingarrangement of the present invention is described in PCT patentapplication publication no. WO 2008/072941 of Applicant published 13Jul. 2006 (see FIGS. 9A, 9B, and 10 and page 17 therein), whichpublication is hereby incorporated by reference in its entirety. Thispublication also describes general features of segments 30 and implant10 although without the stable and secure locking arrangement of thepresent invention.

As seen in FIG. 13, the present invention may also be described as amethod 100 for deploying an implant within a subject's body. Method 100may comprise a first step 110 of providing an implant body including aplurality of segments hingedly interconnected so as to assume astraightened state, and deflectable to assume a flexed deployed state, aplurality of said segments each having an engagement element. In afurther step 120, method 100 may involve providing a locking elementanchored to a distal segment, the locking element extending along theimplant body along a direction of elongation of the implant body. Thelocking element may have projections corresponding to each of theengagement elements of the implant body. In step 130 at method 100, theimplant body may be advanced into the subject's body. Further, rearwardtension may be applied on the locking element such that the implant bodyis deflected to the flexed deployed state. The projections may therebymate with corresponding engagement elements so as to lock correspondingsegments in the flexed deployed state. Some versions of method 100 mayalso include a step of releasing the locking element from its anchor andpulling out the locking element from the medical device.

Structurally, the flexion regions hinges 35 between segments 30 may beimplemented in a wide range of ways. Most preferably, theinterconnection between segments 30 may be a hinged interconnection,which may be is achieved by integral hinges 36 integrally formed withsegments 30 either during an injection or molding process, or throughcutting out of recesses from an initial block of material. The recessesmay be V-shaped notches, parallel sided, or any other suitable form.Most preferably, V-shaped slots are used so that the curved deployedform of the implant has the spaces between the segments essentiallyclosed. However, alternative implementations, such as where the hingedinterconnection is provided by a separate structure 39 (e.g., a“backbone”) to which segments 30 are attached, also fall within thescope of the present invention. In the latter case, the backbone may beof a different material from the segments themselves, chosen accordingto the intended application. Options for materials for the backboneinclude, but are not limited to, metallic materials, various plasticsand other polymers and fabrics.

The flexed deployed state is also referred to as the curved deployedform. However, the “flexing” referred to herein does not necessarilyinvolve actual bending of the segments, although there could be suchbending in some embodiments. Moreover, the curved deployed form shouldnot be understood as necessarily representing a perfect curve,particularly when examined through relatively small numbers of segments.Accordingly, the flexed deployed form, which is called the curveddeployed form of implant body 10 is preferably a roughly arcuate form,and it may typically extend around about 180 degrees to form whatappears as a substantially “U-shaped” form. The term “U-shaped” is usedherein to refer generically to any shape which has a medial portionwhich turns through roughly 180 degrees (i.e., 180 degrees plus or minus20 degrees) without specifying in detail the shape, geometry or extentof the two side portions. (It is noted parenthetically that the letter“u” itself is asymmetric in many typefaces.). It will be appreciatedthat the above descriptions are intended only to serve as examples, andthat many other embodiments are possible within the scope of the presentinvention as defined in the appended claims.

What is claimed is:
 1. A medical device comprising: (a) an implant bodyincluding a backbone and including a plurality of segmentsinterconnected at least by virtue of being commonly attached to thebackbone, so that the implant body assumes a straightened state and aflexed deployed state, a segment of said plurality of segments having anengagement element; and (b) an elongated locking element anchored at onesegment of said implant body, the locking element having a projectioncorresponding to the engagement element, wherein said implant body andsaid locking element are configured to lock, such that when said lockingelement is deflected to reach said flexed deployed state of the implantbody, the projection of the locking element engages and locks with theengagement element of the implant body to lock said locking elementrelative to said implant body, thereby retaining said medical device insaid flexed deployed state, wherein at least one additional segment ofsaid implant body has an additional engagement element and saidelongated locking element has at least one additional projection thatengages and locks with the additional engagement element when said atleast one additional segment of said implant body flexes, said implantbody and said locking element being configured such that, when saidimplant body is deflected, each successive segment of said implant bodyflexes, and projections engage said engagement elements only for thosesegments that have already flexed.
 2. The medical device of claim 1,wherein each of at least three of the segments of said implant body areformed with at least one engagement element from among the engagementelement and the at least one additional engagement element, and thelocking element has a projection corresponding to and engaging at leastone of the engagement elements of the implant body from among theengagement element and the at least one additional engagement element toprovide said locking arrangement.
 3. The medical device of claim 1,wherein each of at least one-third of the segments of said implant bodyare formed with at least one engagement element from among theengagement element and the at least one additional engagement element,and the locking element has a projection corresponding to and engagingeach of the engagement elements of the implant body from among theengagement element and the at least one additional engagement element toprovide said locking arrangement.
 4. The medical device of claim 1,wherein in any group of four consecutive segments, at least one out ofthe four consecutive segments has an engagement element from among theengagement element and the at least one additional engagement element,and locks with a corresponding projection of the locking element.
 5. Themedical device of claim 1, wherein each of the segments of said implantbody other than a distal segment is formed with at least one engagementelement from among the engagement element and the at least oneadditional engagement element, and the locking element has a projectioncorresponding to and engaging at least two of the engagement elements ofthe implant body from among the engagement element and the at least oneadditional engagement element.
 6. The medical device of claim 1, whereina majority of segments of the plurality of segments are formed with atleast one engagement element from among the engagement element and theat least one additional engagement element, and the locking element hasa projection corresponding to each of the at least one engagementelement.
 7. A medical device comprising: (a) an implant body including abackbone and including a plurality of segments interconnected at leastby virtue of being commonly attached to the backbone, so that theimplant body assumes a straightened state and a flexed deployed state, asegment of said plurality of segments having an engagement element; and(b) an elongated locking element anchored at one segment of said implantbody, the locking element having a projection corresponding to theengagement element, wherein said implant body and said locking elementare configured to lock, such that when said locking element is deflectedto reach said flexed deployed state of the implant body, the projectionof the locking element engages and locks with the engagement element ofthe implant body to lock said locking element relative to said implantbody, thereby retaining said medical device in said flexed deployedstate, wherein: the engagement elements of the implant body comprise atleast two sockets, each of at least two different segments having asocket; and the projections of the locking element comprise at least twobulges, the at least two bulges corresponding to the at least twosockets, wherein said implant body and said locking element areconfigured to lock such that when said locking element is deflected toreach said flexed deployed state the at least two bulges of the lockingelement engage and lock with the at least two sockets of the implantbody by said at least two bulges occupying said at least two sockets,and such that said locking element is locked relative to said implantbody in a plurality of segments.
 8. The medical device of claim 7,wherein each of at least half of the segments of said implant body isformed with at least one socket and wherein the tightening element has abulge corresponding to substantially all of the sockets to provide saidlocking arrangement.
 9. The medical device of claim 7, wherein a lengthfrom bulge to nearest adjacent bulge is shorter than a length from aflexion region of a segment to a flexion region of an adjacent segment.10. The medical device of claim 7, wherein the length from bulge tobulge is substantially uniform and wherein the length from socket tosocket is substantially uniform.
 11. The medical device of claim 7,wherein in the straightened state at least some of the bulges of thetightening element are situated in portions of flexion regions outsidethe sockets and in the flexed deployed state the bulges of thetightening element are situated in the sockets of flexed segments. 12.The medical device of claim 7, wherein in the flexed deployed state,every flexed segment that has a socket also has a bulge situatedtherein.
 13. The medical device of claim 7, wherein the medical deviceis helical.
 14. The medical device of claim 7, further including aconduit sized to receive said medical device and to maintain saidimplant body in said straightened state.
 15. The medical device of claim7, wherein the bulges and the sockets are spherical.
 16. A method fordeploying a medical device within a subject's body, comprising:providing an implant body including a backbone and a plurality ofsegments, the segments interconnected at least by virtue of beingcommonly attached to the backbone, so that the implant assumes astraightened state and a flexed deployed state, each of theinterconnected segments having an engagement element; providing alocking element anchored to one of at least two different segments ofthe plurality of segments and extending along said implant body along adirection of elongation of the implant body, the locking element havingprojections corresponding to each of the engagement elements; andadvancing the implant body into the subject's body and applying rearwardtension on said locking element such that the implant body is deflectedto said flexed deployed state, wherein said projections mate withcorresponding one of said engagement elements so as to lockcorresponding segments in said flexed deployed state, such that, whensaid implant body is deflected, each successive segment of said implantbody flexes, and projections engage said engagement elements only forthose segments that have already flexed, further comprising releasingthe locking element from an anchor and pulling out the locking elementfrom the implant body.
 17. A medical device comprising: an implant bodyincluding a plurality of segments interconnected so as to assume astraightened state of the implant body and a flexed deployed state ofthe implant body, one of said segments having an engagement element; andan elongated locking element anchored at one segment of said implantbody, the locking element having a projection corresponding to theengagement element, wherein said implant body and said locking elementare configured to lock, such that when said locking element is deflectedto reach said flexed deployed state of the implant body, the projectionof the locking element engages and locks with the engagement element ofthe implant body to lock said locking element relative to said implantbody, thereby retaining said medical device in said flexed deployedstate, wherein: (a) the engagement element and additional engagementelements of the implant body comprise at least two sockets, each of atleast two different segments having a socket; and (b) the projections ofthe locking element comprise at least two bulges, the at least twobulges corresponding to the at least two sockets, wherein said implantbody and said locking element are configured to lock such that when saidlocking element is deflected to reach said flexed deployed state the atleast two bulges of the locking element engage and lock with the atleast two sockets of the implant body by said at least two bulgesoccupying said at least two sockets, and such that said locking elementis locked relative to said implant body in a plurality of segments. 18.The medical device of claim 17, wherein at least one additional segmentof said implant body has an additional engagement element and saidelongated locking element has at least one additional projection thatengages and locks with the additional engagement element when said atleast one additional segment of said implant body flexes, said implantbody and said locking element being configured such that, when saidimplant body is deflected, each successive segment of said implant bodyflexes, and projections engage said engagement elements only for thosesegments that have already flexed.
 19. A medical device comprising: animplant body including a plurality of segments, the plurality ofsegments configured to be commonly attached to a backbone that engagesthe medical device, and in being so attached the plurality of segmentsbeing interconnected such that the implant body assumes a straightenedstate and a flexed deployed state, one of said segments having anengagement element; and an elongated locking element anchored at onesegment of said implant body, the locking element having a projectioncorresponding to the engagement element, wherein said implant body andsaid locking element are configured to lock, such that when said lockingelement is deflected to reach said flexed deployed state of the implantbody, the projection of the locking element engages and locks with theengagement element of the implant body to lock said locking elementrelative to said implant body, thereby retaining said medical device insaid flexed deployed state, wherein at least one additional segment ofsaid implant body has an additional engagement element and saidelongated locking element has at least one additional projection thatengages and locks with the additional engagement element when said atleast one additional segment of said implant body flexes, said implantbody and said locking element being configured such that, when saidimplant body is deflected, each successive segment of said implant bodyflexes, and projections engage said engagement elements only for thosesegments that have already flexed.